In a first experiment mice infected intravenously with 106 Mycobacterium tuberculosis were randomly treated either with isoniazid (INH) + rifampicin (RMP) 25 mg/kg or with INH + RMP + pyrazinamide (PZA) or with INH + RMP + PZA + streptomycin (SM). The decrease of the viable counts (CFU) in the lungs was similar with all three regimens. In a second experiment, mice were treated for 6 months either with INH + RMP 25 mg/kg or INH + RMP 10 mg/kg. After a follow-up of 6 months, mice were killed and their lungs and spleen cultivated. Positive cultures were obtained in 7.5% of the mice treated with the high dose of RMP and 36.5% in the mice treated with the low dose (p < 0.05). A third experiment demonstrated that, during the first 2 months of treatment, adding PZA to INH + RMP 10 mg/kg increased significantly the overall effectiveness of INH + RMP 10 mg/kg combination. A fourth experiment demonstrated that after 3 initial months of INH + RMP 10 mg/kg, RMP alone was as effective as RMP + INH or RMP + INH + PZA. It may be concluded that RMP and PZA are both active on the intracellular population of Mycobacterium tuberculosis and that RMP is the only drug to act on persisting Mycobacterium tuberculosis in extracellular lesions.
|Number of pages||5|
|State||Published - Jan 1 1982|
ASJC Scopus subject areas
- Pathology and Forensic Medicine